Ground fault circuit interrupting (GFCI) devices, as currently available, are capable of interrupting fault current in the range of 4 to 6 milliamps. Circuits for such devices are described in U.S. Pat. Nos. 4,345,289 and 4,348,708, both of which are in the name of Edward K. Howell. The circuits described therein basically include a current sensor or magnetics, a signal processor or electronics and an electronic switch. The magnetics consist of a differential current transformer which responds to a current imbalance in the line and neutral conductors of the distribution circuit. This current imbalance is amplified by the signal processor pursuant to triggering the electronic switch and thereby complete an energization circuit for the trip solenoid. The current sensor also includes a neutral excitation transformer for responding to a ground fault on the neutral conductor.
A mounting arrangement for the GFCI device is described in U.S. Pat. Nos. 3,950,677 and 4,001,652 to Keith W. Klein et al. In the Klein et al. GFCI device, the signal processor electronics is carried on a printed wire board and is positionally mounted and retained in one shell compartment of a GFCI receptacle casing. The magnetics are positionally mounted in another shell compartment within the receptacle and are locked in place by the insertion of single turn transformer winding elements. This GFCI assembly, although compact, does not readily lend to a fully automated assembly process since the magnetics contain two separate transformers which require electrical interconnection with each other as well as with the circuit electronics. To date, the electrical interconnection of the magnetics with the electronics has accounted for a good percentage of the time involved in the GFCI assembly process.
The grounding and push-to-test arrangement for the Klein et al. GFCI device is fully described within U.S. Pat. No. 4,010,432, also in the name of Keith W. Klein et al., which patent is incorporated herein for purposes of reference. This patent discloses means for attaching the faceplate yoke to the case for providing connection with system ground through a ground receptacle slot. Also disclosed is an arrangement for providing push-to-test facility whereby depression of a test button causes simulated ground leakage current to flow and to trip and deenergize the receptacle sockets. Reference to this patent should be made for a more complete description of the state of the art of ground and test arrangements for GFCI devices.
The purpose of this invention is to provide a combination receptacle stab-interrupter moveable contact and push-to-test arrangement for automated assembly within a GFCI housing without wires or braids, and also to provide a plug-on integral grounding yoke with self-grounding features.